To date, contact lenses (hereinafter includes both soft types and hard types) have been widely used for correcting refractive power of the human eye, but nevertheless there always exists the possibility of some defect occurring during the life of the lens. For example, a contact lens can become contaminated by proteins or lipids that become deposited on it, or experience morphological defects such as deformation or chipping, or become damaged through scratching or cracking. These instances are by no means rare.
Problems resulting from such defects are not limited to reduced wear comfort and impaired vision, but also pose the risk of severe problems such as damage to the user's cornea.
Defects occurring in contact lenses such as those mentioned above may not just be readily noticeable to the user. In the case of soft contact lenses in particular, deposited contaminants, or even morphological defects or scratches, may not be noticeable at all to the user or may not be recognized as a significant problem, in certain instances, so that the user continues to use the defective lens over an extended period.
To solve such problems, it would be possible, for example, to compel periodic examination of contact lenses by the user himself or by bringing the lenses to a dealer shop or the like, but such measures are not effective in practical terms. That is, in many instances, it is difficult to inspect contact lenses for the occurrence of defects like those mentioned above, and in particular since in most cases the user needs to always wear contact lenses, it is not practical to send the lenses in to a dealer shop for inspection. In addition to this, there has been no effective method by which contact lenses currently used by a user can be inspected for defects and the like.
Methods for assessing the extent of contamination of a contact lens by proteins or lipids are disclosed inter alia in JP-A-9-15155 and JP-A-11-94795. However, as each of these methods involves detecting total quantity of proteins or lipids separated and extracted from a lens, the detection operation involves the use of special extraction solutions and the like, making it difficult and time-consuming, as well as being unable to discern the extent of localized contaminant deposits or the condition of distribution of deposits on a contact lens, so that such methods are not easy utilized by the user.
Another method that has been considered involves soaking the lens in a staining reagent that selectively stains a particular type of contaminants, and observing the stained areas on the lens and the shade thereof. However, as this method involves the use of a special reagent or the like, the detection procedure remains very complicated and requires specialized knowledge for proper observation of the results, making this method impractical as well.
For protein deposits and the like, in most cases routine care (e.g. periodic removal of deposits or the like) and lens replacement are required, but such measures are necessarily effective only for certain specific types of contaminants. Additionally, with regard to protein deposits and the like, the extent of contamination of a contact lens will vary appreciably not only due to differences in the makeup of lachrymal fluid among different users, but also depending on the number of hours the lens is worn in a day, the user's surroundings, and various other conditions, so that such measures will not necessarily be effective for all users.
With the foregoing in view the invention has been developed, it is an object of the present invention to provide a novel support method and support system for contact lens users whereby, for contact lenses that to date care of which has been left up to the user exclusively with virtually no appropriate support being provided after the sale, users may now be provided on an individual basis with appropriate support, and afforded comfortable contact lens wear thereby.
It is a further object of the invention to provide a novel support method and support system for contact lens users whereby through appropriate support after sale of contact lenses, defects such as contamination of or damage to contact lenses may be readily checked by the user himself.